|First appearance||Batman: The Return #1, (January 2011)|
Grant Morrison (writer)|
David Finch (artist)
|Type of organization||Organized crime, terrorist|
|Leader(s)||Talia al Ghul|
Dr. Dedalus (Otto Netz)|
The Heretic (Fatherless)
Son of Pyg
Leviathan is a shadowy organization with origins unknown, capable of creating surgically and genetically altered super-humans. They've also shown an ability to brainwash people for their cause.
While the head of the organization is unknown, one notable agent of Leviathan is The Heretic, a mysterious figure Batman and Damian Wayne came across in Yemen, dressed in an Arab Batman garb. When Damian initially discovers him, The Heretic gives him a haunting message of "You will know me. But not yet..." 
Batman immediately connected the organization to an apocalyptic vision he'd received while coming back from the dead, and positioned his newly formed Batman Incorporated organization to oppose them. After some moves, Leviathan seemed to form up behind Doctor Dedalus, a Nazi masterspy imprisoned on the Falkland Islands, with a predicted lifespan of months due to Alzheimers. In the aftermath of Dedalus' breakout, further investigation showed that a paper-trail, such as it was, showed a flow of child soldiers from training camps in the central African republic of Mtamba (the location of fellow Batman Inc. member Batwing) to locations around the world, for use by Leviathan in their campaign. Their leader is revealed to be Talia al Ghul.
- Talia Head- Head of Leviathan.
- Professor Pyg - Lazlo Valentin at first appears to be working for Simon Hurt, but it is later revealed his 'mother' is Talia al Ghul.
- The Heretic (Fatherless)- Mysterious agent of Leviathan, in a bat like costume. The Heretic is a clone of Damian Wayne, first seen as a fetus in the first volume of Batman and Robin, whose growth has been accelerated to adulthood by way of a bio-engineered whale carcass.
- Son of Pyg- Son of Professor Pyg . Real name Janosz Valentin aka Johnny Valentine.
- Dr. Dedalus (Otto Netz)- Former Nazi scientist, and agent of Leviathan and the biological father of Kathy Kane, the original Batwoman. Later killed by the new Robin using a concealed knife.
- Goatboy- Gotham City bred taxi-driver, turned assassin in light of Talia's billion dollar bounty on Damian.